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Date: Tue, 20 Feb 2018 16:50:07 +0200
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: John Garry <john.garry@...wei.com>
Cc: Mika Westerberg <mika.westerberg@...ux.intel.com>,
"Rafael J. Wysocki" <rafael@...nel.org>,
Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Hanjun Guo <hanjun.guo@...aro.org>,
Rob Herring <robh+dt@...nel.org>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Arnd Bergmann <arnd@...db.de>,
Mark Rutland <mark.rutland@....com>,
Olof Johansson <olof@...om.net>,
Dann Frazier <dann.frazier@...onical.com>,
Rob Herring <robh@...nel.org>, Joe Perches <joe@...ches.com>,
Benjamin Herrenschmidt <benh@...nel.crashing.org>,
linux-pci@...r.kernel.org,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
Linuxarm <linuxarm@...wei.com>, Corey Minyard <minyard@....org>,
devicetree <devicetree@...r.kernel.org>,
Linux-Arch <linux-arch@...r.kernel.org>,
Randy Dunlap <rdunlap@...radead.org>
Subject: Re: [PATCH v14 6/9] HISI LPC: Support the LPC host on Hip06/Hip07
with DT bindings
On Mon, Feb 19, 2018 at 7:48 PM, John Garry <john.garry@...wei.com> wrote:
> From: Zhichang Yuan <yuanzhichang@...ilicon.com>
>
> The low-pin-count(LPC) interface of Hip06/Hip07 accesses the peripherals in
> I/O port addresses. This patch implements the LPC host controller driver
> which perform the I/O operations on the underlying hardware.
> We don't want to touch those existing peripherals' driver, such as ipmi-bt.
> So this driver applies the indirect-IO introduced in the previous patch
> after registering an indirect-IO node to the indirect-IO devices list which
> will be searched in the I/O accessors to retrieve the host-local I/O port.
>
> The driver config is set as a bool instead of a trisate. The reason
> here is that, by the very nature of the driver providing a logical
> PIO range, it does not make sense to have this driver as a loadable
> module. Another more specific reason is that the Huawei D03 board
> which includes hip06 SoC requires the LPC bus for UART console, so
> should be built in.
> +config HISILICON_LPC
> + bool "Support for ISA I/O space on Hisilicon hip06/7"
> + depends on (ARM64 && (ARCH_HISI || COMPILE_TEST))
Redundant parens.
> + select INDIRECT_PIO
> + help
> + Driver needed for some legacy ISA devices attached to Low-Pin-Count
> + on Hisilicon hip06/7 SoC.
> +#if LPC_MAX_DULEN > LPC_MAX_BURST
> +#error "LPC.. MAX_DULEN must be not bigger than MAX_OPCNT!"
> +#endif
But here you can easily avoid an #error, by making them equal, just
issue a warning instead.
> +#if LPC_MAX_BURST % LPC_MAX_DULEN
> +#error "LPC.. LPC_MAX_BURST must be multiple of LPC_MAX_DULEN!"
> +#endif
Is it like this, or also should be power of two?
> +/* The command register fields */
> +#define LPC_CMD_SAMEADDR 0x08
> +#define LPC_CMD_TYPE_IO 0x00
> +#define LPC_CMD_WRITE 0x01
> +#define LPC_CMD_READ 0x00
> +/* the bit attribute is W1C. 1 represents OK. */
> +#define LPC_STAT_BYIRQ 0x02
BIT() ?
> +#define LPC_STATUS_IDLE 0x01
> +#define LPC_OP_FINISHED 0x02
> +
> +#define LPC_START_WORK 0x01
Ditto?
> +static inline int wait_lpc_idle(unsigned char *mbase,
> + unsigned int waitcnt) {
> + u32 opstatus;
> +
> + while (waitcnt--) {
> + ndelay(LPC_NSEC_PERWAIT);
> + opstatus = readl(mbase + LPC_REG_OP_STATUS);
> + if (opstatus & LPC_STATUS_IDLE)
> + return (opstatus & LPC_OP_FINISHED) ? 0 : (-EIO);
> + }
> + return -ETIME;
Personally I prefer timeout loops in a do {} while (--count) style.
> +}
> +static int
> +hisi_lpc_target_in(struct hisi_lpc_dev *lpcdev, struct lpc_cycle_para *para,
> + unsigned long addr, unsigned char *buf,
> + unsigned long opcnt)
> +{
> + unsigned int cmd_word;
> + unsigned int waitcnt;
> + unsigned long flags;
> + int ret;
> +
> + if (!buf || !opcnt || !para || !para->csize || !lpcdev)
> + return -EINVAL;
> +
> + cmd_word = LPC_CMD_TYPE_IO | LPC_CMD_READ;
> + waitcnt = LPC_PEROP_WAITCNT;
> + if (!(para->opflags & FG_INCRADDR_LPC)) {
> + cmd_word |= LPC_CMD_SAMEADDR;
> + waitcnt = LPC_MAX_WAITCNT;
> + }
> +
> + ret = 0;
> +
Sounds redundant.
> + /* whole operation must be atomic */
> + spin_lock_irqsave(&lpcdev->cycle_lock, flags);
> +
> + writel_relaxed(opcnt, lpcdev->membase + LPC_REG_OP_LEN);
> +
> + writel_relaxed(cmd_word, lpcdev->membase + LPC_REG_CMD);
> +
> + writel_relaxed(addr, lpcdev->membase + LPC_REG_ADDR);
> +
> + writel(LPC_START_WORK, lpcdev->membase + LPC_REG_START);
> +
> + /* whether the operation is finished */
> + ret = wait_lpc_idle(lpcdev->membase, waitcnt);
> + if (!ret) {
I would rather go with usual pattern
if (ret) {
...
return ret;
}
> + for (; opcnt; opcnt--, buf++)
> + *buf = readb(lpcdev->membase + LPC_REG_RDATA);
Looks like a do {} while (slightly better for my opinion).
do {
*buf++ = readb(lpcdev->membase + LPC_REG_RDATA);
} while (--opcnt);
> + }
> +
> + spin_unlock_irqrestore(&lpcdev->cycle_lock, flags);
> +
> + return ret;
> +}
> + for (; opcnt; buf++, opcnt--)
> + writeb(*buf, lpcdev->membase + LPC_REG_WDATA);
Ditto.
> +static u32 hisi_lpc_comm_in(void *hostdata, unsigned long pio, size_t dwidth)
> + if (!lpcdev || !dwidth || dwidth > LPC_MAX_DULEN)
> + return -1;
~0 ?
> + if (ret)
> + return -1;
Ditto.
> + do {
> + int ret;
> +
> + ret = hisi_lpc_target_in(lpcdev, &iopara, addr,
> + buf, dwidth);
> + if (ret)
> + return ret;
> + buf += dwidth;
> + count--;
> + } while (count);
} while (--count);
> + do {
> + if (hisi_lpc_target_out(lpcdev, &iopara, addr, buf,
> + dwidth))
> + break;
> + buf += dwidth;
> + count--;
> + } while (count);
Ditto.
> +static int hisi_lpc_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct acpi_device *acpi_device = ACPI_COMPANION(dev);
> + struct logic_pio_hwaddr *range;
> + struct hisi_lpc_dev *lpcdev;
> + struct resource *res;
> + int ret = 0;
Redundant assignment.
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (!res)
> + return -ENODEV;
Redundant.
> +
> + lpcdev->membase = devm_ioremap_resource(dev, res);
> + if (IS_ERR(lpcdev->membase)) {
> + dev_err(dev, "remap failed\n");
Redundant.
> + return PTR_ERR(lpcdev->membase);
> + }
> + /* register the LPC host PIO resources */
> + if (!acpi_device)
> + ret = of_platform_populate(dev->of_node, NULL, NULL, dev);
> + if (ret) {
> + dev_err(dev, "populate children failed (%d)\n", ret);
JFYI: ret is printed by device core if ->probe() fails.
> + return ret;
> + }
This condition should go under if (!acpi_device) case.
--
With Best Regards,
Andy Shevchenko
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